Trinity

This was one of the most abstract and speculative works published by Infocom--and, in my opinion, one of the most difficult to solve as well. It managed to combine an Alice-in-Wonderland feel with a story about the invention of the Atomic Bomb, with some time, space, and interdimensional travel thrown in to boot. It also managed, as few games at the time did, to make some social commentary in the process. Overall, a unique and challenging game, and one that will make you think--not just about the puzzles, but about life and the consequences of our actions.